Rugalmas rácsok kollektiv dinamikája rendezetlen potenciál térben = Collective Dynamics of Elastic Lattices in Disorder Potential

A projekt keretében nagyáramú transzportméréseket végeztünk a magashőmérsékletű szupravezetők prototípusának tekinthető Bi2Sr2CaCu2O8 (BSCCO) egykristályokon. Vizsgálataink a következő új eredményekhez vezettek: 1. Az alacsonyhőmérsékleti vortexüveg fázis egy tartományában megfigyelt metastabil viselkedés megjelenése nem fázisátmenet, hanem egy dinamikus átmenetet, amely során a vortexek termikus relaxációs ideje hosszabbá válik, mint a kísérlet időskálája. 2. A disszipáció a szupravezető és normális állapotot elválasztó front mozgásával fokozatosan terjed a mintában. 3. A szabad vortexmozgás (FFF) disszipatív dinamikája nem írható le a széleskörűen elfogadott Bardeen-Stephen-törvénnyel, amely szerint az ellenállás lineárisan közelít a nem szupravezető értékhez, ha a mágneses tér a felső kritikus mágneses térhez tart, hanem egy 3/4 kitevőjű hatványfüggvénnyel irható le. 4. A szilárd vortex fázisban a mágneses ellenállás telítődik nagy mágneses térnél. A jelenséget a szomszédos szupravezető síkokon a vortexmagok közötti kvázirészecske-vezetőképesség segítségével értelmeztük. 5. Szilárd vortex fázisban nagy áramoknál Hall-feszültség jelenik meg, mely előjelet vált a mágneses tér irányának változtatásakor. A Hall-feszültség megjelenésének küszöbárama két nagyságrenddel nagyobb, mint a longitudinális feszültségé. A jelenséget a vortexek dinamikus rendeződésével értelmeztük. | Our programme on high current electrical transport in Bi2Sr2CaCu208 (BSCCO), chosen as the prototypical high Tc cuprate superconductor, has brought new understanding to several aspects: 1.The portion of the low temperature vortex glass phase exhibiting metastability is not a new phase but a dynamic crossover at which thermal relaxation of the vortices into the disorder slows to the time scale of the experiments. 2. Dissipation sets in progressively as a superconducting/normal front moves into the sample. 3.The free flux flow viscous dynamics does not obey the widely accepted Bardeen- Stephen law that the resistivity approach its non-superconducting value linearly with field to the upper critical field, but rather a displays a 3 power law. 4.The magneto resistance in the vortex solid phase saturates at high field. This is interpreted as arising from extra c-axis conduction along the cores of vortices which have time averaged out the disorder and become aligned from plane to plane to displace as a 3-D Abrikosov like solid. 5.In the vortex solid phase a real Hall potential, one which changes sign on magnetic field reversal, appears only at very high currents, two orders of magnitude beyond the depinning threshold. We ascribe this to motion along a channel from which escape into unguided free flux flow exhibiting a real Hall effect requires a minimum lateral force. The large factor between depinning and dechanneling is attributed to the increased current penetration accompanying vortex alignment

Disszipáció másodfajú szupravezetőkben = Dissipation in type-II superconductors

A szupravezetőkben szélsőséges körülmények között disszipáció jelenik meg, azaz megszűnik ideális vezető tulajdonságuk. Az ilyen disszipatív folyamatokat vizsgáltuk elsősorban magashőmérsékleti szupravezetőkben. Megmutattuk, hogy a disszipációt az Abrikoszov-féle örvények és a szupravezető rétegek közötti Josephson-féle alagutazás mindig együtt határozza meg. Vizsgáltuk a kvázirészecskék szerepét is az ún. nemkonvencionális szupravezetőkben és több transzporttulajdonságra kaptunk újszerű eredményeket. Vizsgáltuk azt az érdekes és megfejtetlen jelenséget, hogy a magashőmérsékleti szupravezetőkben gyakran már a fémes fázisban lecsökken az állapotsűrűség. Analógiát kerestünk a jelenségre egy egydimenziós fémben és úgy találtuk, hogy ebben az esetben az állapotsűrűség lecsökkenését egy rejtett (nehezen megfigyelhető) rend kialakulása okozza. | Under extreme conditions, dissipation appears in superconductors, i.e., they cease to be ideal conductors. We have investigated these dissipative processes mainly in high-critical-temperature superconductors. We have shown that the dissipation always arises from both the motion of Abrikosov vortices and the Josephson tunneling between adjacent superconducting layers. We have also investigated the role of quasiparicles in unconventional superconductors and found several novel results on the transport properties of these materials. We have considered the intriguing phenomenon that in certain high-critical-temperature superconductor the density of electronic states starts to decrease already in the metallic phase. To gain insight from an analogy, we have studied the decrease of the density of states in a quasi-one-dimensional conductor. We have shown that in this case the origin of the phenomenon is the formation of a hidden (difficult to observe) order

NORA moving forward: Developing an oyster restoration network in Europe to support the Berlin Oyster Recommendation

1. The Native Oyster Restoration Alliance (NORA) supports the protection and ecological restoration of the native European oyster, Ostrea edulis, and its habitat across its current and historical biogeographical range. NORA works to overcome barriers to the conservation, restoration, and recovery of the European oyster by providing a platform for the NORA community to collaborate and participate in knowledge exchange. NORA seeks to support responsible restoration practice, in compliance with biosecurity and sustainability. 2. Against this background, the NORA community formulated a series of specific recommendations, the Berlin Oyster Recommendation, to support native oyster restoration by developing and applying best practice with the aim to recover healthy and resilient marine ecosystems. In combination with the Standards for Ecological Restoration (SER) and the Restoration Guidelines for Shellfish Reefs, the Berlin Oyster Recommendation is a relevant tool for successful and sustainable oyster restoration in Europe. 3. The establishment of NORA working groups will support the implementation and further development of the six corresponding recommendations. Current NORA working groups cover site selection, biosecurity, production, and monitoring. The site selection working group will address the identification of suitable sites for oyster restoration to support policy relevant decision making and the conservation, reinforcement, or reintroduction of native oysters. The biosecurity working group will develop biosecurity guidelines for native oyster restoration in Europe. The production working group will assess the potential of standards for seed oyster production and supply in order to enhance production appropriate for restoration purposes. In close collaboration with the Native Oyster Network – UK & Ireland (NON), the monitoring working group will produce a monitoring guidelines handbook to provide metrics and methods that will be suitable across the range of O. edulis projects in Europe for the documentation of restoration success and ecosystem recovery. 4. The Berlin Oyster Recommendation was examined and interpreted by NORA experts in the context of the further development of joint guidelines for the practice of successful and sustainable native oyster restoration

Bonamia infection in native oysters (Ostrea edulis) in relation to European restoration projects

1. There is a growing effort throughout Europe to restore populations of native oysters (Ostrea edulis), with the ecological objective of enhancing ecosystem biodiversity and resilience. 2. The introduced parasite, Bonamia ostreae, caused catastrophic mortalities during the 1980s, furthering the decline of this species, and is now present throughout much of the natural range of O. edulis. It is therefore important that restoration attempts avoid further introduction and spread of this parasite, which can cause lethal infections of O. edulis. 3. This article presents a comprehensive overview of the scale and distribution of current infection, transmission pathways, and preventive measure guidelines, focusing on the seas, inlets, and estuaries of north‐west Europe, where most ecological restoration attempts for the native European oyster have occurred so far. 4. This is critical information for restoration project planning in which the risk of Bonamia infection must be taken into account

Ten priority questions for increasing the consistency and success in hatchery production of the European flat oyster for habitat restoration

The European flat oyster, Ostrea edulis, once formed extensive reef habitats throughout European seas and estuaries. These reefs are now largely functionally extinct, yet interest and support for their restoration is rapidly growing. A major bottleneck to scaling up oyster reef restoration is the lack of available oysters to supply the growing demand. This study aimed to identify the ten questions which, if answered, would increase the consistency and success in hatchery production of O. edulis for habitat restoration. Candidate questions were submitted by representatives from twelve commercial and research hatcheries across Europe. The list of 98 candidate questions were collaboratively discussed by experts from nine research hatcheries across eight countries in Europe, to identify the top ten questions via an iterative and open process. Questions were grouped into the following themes: conditioning and feeding, larval rearing, disease and water quality, hatchery protocol, genetics, and hatchery management. There were several overarching topics spanning these themes, including diet optimisation, maximising the effective population size, and developing the technical skillbase in order to increase hatchery production to meet the projected increase in demand for oyster seed for habitat restoration efforts. We anticipate this list will provide a starting point for collaborative research efforts across Europe, as well as assisting policy makers and funders in identifying key knowledge gaps

EVS Trend File 1981-2017 – Sensitive Dataset

The European Values Study is a large-scale, cross-national and longitudinal survey research program on how Europeans think about family, work, religion, politics, and society. Repeated every nine years in an increasing number of countries, the survey provides insights into the ideas, beliefs, preferences, attitudes, values, and opinions of citizens all over Europe. The EVS Trend File 1981-2017 is constructed from the five EVS waves and covers almost 40 years. In altogether 160 surveys, more than 224.000 respondents from 48 countries/regions were interviewed. It is based on the updated data of the EVS Longitudinal Data File 1981-2008 (v.3.1.0) and the current EVS 2017 Integrated Dataset (v.5.0.0). For the EVS Trend File, a Restricted-Use File (ZA7504) is available in addition to the (factually anonymised) Scientific-Use File (ZA7503). The EVS Trend File – Sensitive Dataset (ZA7504) is provided as an add-on file. In addition to a small set of admin and protocol variables needed to merge with the SUF data, the Sensitive Dataset contains the following variables that could not be included in the scientific-use file due to their sensitive nature: W005_3 Job profession/industry (3-digit ISCO88) - spouse/partner EVS 2008W005_3_01 Job profession/industry (3-digit ISCO08) - spouse/partner EVS 2017W005_4 Job profession/industry (4-digit ISCO88) - spouse/partner EVS 2008X035_3 Job profession/industry (3-digit ISCO88) – respondent EVS 1999, EVS 2008 X035_3_01 Job profession/industry (3-digit ISCO08) - respondent EVS 2017X035_4 Job profession/industry (4-digit ISCO88) – respondent EVS 1999, EVS 2008 x048c_n3 Region where the interview was conducted (NUTS-3): NUTS version 2006 EVS 2008X048J_N3 Region where the interview was conducted (NUTS-3): NUTS version 2016 EVS 2017X049 Size of town (8 categories) EVS 2008, EVS 2017 Detailed information on the anonymization process in the EVS Trend File is provided in the EVS Trend File Variable Report